Friday, 11 December 2015

What is Turbine? What Are Main Types of Turbines?

Today we will learn about what is turbine and types of turbines used in industries. We have heard many time the word "turbine" but most of us don't know more about It. Turbine is mostly used in
the hydro power plant and in steam power plant to generate electric power. It is one of the hydraulic machines. Hydraulic machine is defined as those
machines which convert hydraulic energy into mechanical energy or mechanical
energy into hydraulic energy.

What is turbine?

A hydraulic machine which converts hydraulic energy into
mechanical energy is known as turbine. Turbine is a device which transfers
kinetic energy of water, air, gas or steam to the shaft which cause rotates the
shaft. Simply turbine is a rotor which has vanes at the peripheral of it. In
the power plant industries, it is situated at the end of electromagnet (generator)
which causes to rotate it and generate electric power. Turbine is mostly used
in hydroelectric power plant such as dams etc. which is the cheapest method of
power generation.

We know that turbine is mostly used in hydroelectric power
plant. As shown in diagram a dam is constructed across a river to store water. There
is the elevation difference between turbine and dam. Turbine and dam is connected
by a large diameter pipe called penstock which carries water under pressure
from the storage reservoir to the turbine. The turbine is connected to the electromagnet.
Turbine has different types of vanes fitted on rotter. The water under pressure
strikes the turbine, and rotate it, which further rotate the electromagnet or
generator to generate power. The water is carried to tailrace after worked on the
turbine.

Types of Turbines:

Turbine can be classified
according to direction of flowing fluid, head at the inlet of turbine etc. These
are

According to the type of energy at inlet:

1. Impulse turbine:

If the energy available at inlet of turbine is only kinetic energy,
the turbine so known as impulse turbine.
The available energy at inlet is only kinetic energy if the inlet
pressure and outlet pressure is same equal to atmospheric pressure. The water
use only its kinetic energy to rotate the turbine and the pressure of water remain
constant. Pelton wheel turbine is a one of the impulse turbine.

Pelton Wheel Turbine

2. Reaction turbine:

If the pressure at the inlet of turbine and outlet of
turbine is different or the water use its kinetic energy as well as pressure
energy to rotate the turbine is known as reaction turbine. When the water under
pressure flows through the turbine, some of its pressure energy convert into
kinetic energy which rotate the turbine. In this turbine pressure change during
the energy transfer so it is air tight. The Francis and Kaplan turbine is the
example of this turbine.

Kaplan Turbine (Reaction Turbine)

According to the direction of flow through runner:

1. Tangential flow turbine:

If the water flows along the tangent of the runner, the
turbine is known as tangential flow turbine. Pelton wheel turbine is the
example of tangential flow turbine.

2. Radial flow turbine:

If the water flows in the radial direction through the runner,
the turbine is called radial flow turbine. If the water flows from outward to
inward, radially, the turbine is known as inward radial flow turbine and if oppose
the turbine is known as outward radial flow turbine.

3. Axial flow turbine:

If the water flows along the direction parallel to the axis
of the runner, the turbine is known as axial flow turbine. Francis turbine is the
example of axial flow turbine.

4. Mixed flow turbine:

If the water flows through the runner in the radial direction
but leaves in the direction parallel to the axis of rotation of the runner, the
turbine is called mixed flow turbine.

According to head at the inlet of turbine:

1. High head turbine

2. Medium head turbine

3. Low head turbine

According to specific speed of turbine:

1. Low specific speed turbine

2. Medium specific speed turbine3. High specific speed turbine

Today we have learnt about what is turbine and types of turbines. If you have any doubt regarding this article, ask by commenting.